Structural effects of two-dimensional perovskite Ca2Nb2TaO10− nanosheets for photocatalytic hydrogen evolution

Abstract

Restacked nanosheets of Dion–Jacobson perovskite Ca₂Nb₂TaO₁₀⁻ were studied with respect to the structural features as photocatalysts for H₂ evolution from an aqueous methanol solution. The materials were prepared by the reaction of layered HCa₂Nb₂TaO₁₀ with tetra-n-butylammonium hydroxide (TBA⁺OH⁻) at room temperature, followed by restacking with a proper restacking agent. According to structural characterization by means of X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and UV-visible diffuse reflectance spectroscopy, the structural features and the degree of interlayer hydration of the restacked material depended on the restacking agent employed. The highest photocatalytic activity was obtained for the restacked nanosheets using HCl as the restacking agent. Results of structural characterizations and photocatalytic reactions suggested that the high activity resulted from not interlayer hydration but protonation, which is favorable for the oxidation reaction.